Under certain circumstances, ice can form inside of the compressor section of a turbine engine. Ice formation requires both adherence of moisture to a surface and a reduction in temperature. Water can enter a compressor in several ways. For example, water is sometimes injected into the compressor to increase power by wet compression. In some instances, the air drawn into the compressor may be moist because of the prevailing weather conditions (i.e., high humidity). As the air travels through the compressor, the moisture in the air can contact and adhere to various surfaces in the compressor, such as to a stationary vane.
There are situations in which the temperature of the air in the compressor can drop to or below the freezing point of water. For instance, when the inlet guide vanes are closed beyond certain values, a large pressure drop can occur, which, in turn, can induce a corresponding drop in the temperature of the air flowing though the compressor. These conditions can foster the formation of ice on the surface of the vane. If the ice dislodges from the vane during engine operation, the ice can impact and damage other components in the compressor, such as blades and other vanes. Such damage can result in time-consuming, labor intensive and costly repairs. Thus, there is a need for a system that can at least detect the presence of moisture and/or ice on at least a part of the surface of a compressor airfoil.